Conventional magnetic disk drives are information storage devices which utilize at least one rotatable magnetic media disk with concentric data tracks, a read/write transducer for reading and writing data on the various tracks, an air bearing slider for holding the transducer adjacent to the track generally in a flying mode above the media, a suspension for resiliently holding the slider and the transducer over the data tracks, and a positioning actuator connected to the suspension for moving the transducer across the media to the desired data track and maintaining the transducer over the data track during a read or a write operation.
The recording density of a magnetic disk drive is limited by the distance between a transducer and the magnetic media. One goal of air bearing slider design is to "fly" a slider as closely as possible to a magnetic medium while avoiding physical impact with the medium. Smaller spacings, or "fly heights", are desired so that the transducer can distinguish between the magnetic fields emanating from closely spaced regions on the disk.
An important criteria in slider fabrication is to be able to produce an ABS contour that performs well in the head/disk interface. It is known that a positive crown on the slider ABS will improve the dynamic performance of the slider, such as improving fly height and improving take-off, at the head/disk interface. A positive crown, however, is not achievable using conventional lapping apparatus and processes.
Previously, a positive crown has been achieved on air bearing surfaces by using a crown adjust process, such as sandblasting or laser scribing at the row level, after lapping of the ABS was complete. While these processes have performed reasonably well, they do have many limitations. For instance, the limited area that one can do sandblasting, especially with pico and smaller air bearings, the ABS damage due to misalignment during sandblasting, and the material properties of the slider, all tend to limit the capability of conventional crown adjust processes. These known crown adjust processes can also cause yield detractions and tend to increase slider cost.
Prior publications which are exemplary of previous techniques for contouring surfaces include Biskeborn et al., U.S. Pat. No. 5,603,156. Biskeborn et al. disclose a lapping process used on slider air bearing surfaces which minimizes electrical shorts resulting from smearing of electrically active elements at the air bearing surface. The lapping process further reduces the magnitude of recession of head elements at the air bearing surface. In one embodiment, the air bearing surface is contoured by rocking a magnetic tape recording head on a rotating lapping plate, thereby forming a curved air bearing surface. In an alternative embodiment, the magnetic tape recording head is moved across a lapping tape to produce the curved air bearing surface. However, in each of these processes, the heads are lapped individually instead of being row processed.
Published Japanese Patent Application No. 60-155,353 discloses a chamfering process in which a workpiece swings about a first axis as the workpiece is brought into engagement with rotating cutting members, including a lapping tape. Stability of the surface to be machined and improved productivity are obtained by this process.
Schneider, U.S. Pat. No. 3,499,214, discloses a process of contouring a ridge on a magnetic head by swinging the head about a first axis relative to a rotating lapping plate. The process is particularly directed toward fabricating a contact surface between the magnetic head and a magnetic storage medium.
Reibakh, U.S. Pat. No. 4,617,764, discloses a machine for contouring three dimensional surfaces of workpieces. Wikle, U.S. Pat. No. 5,503,589, discloses an apparatus for grinding and contouring gas turbine blades.
There exists a continuing need, however, for improved apparatus and techniques for contouring workpiece surfaces, particularly for producing a positive crown on a slider ABS. It would be desirable if the ABS crown was produced during lapping of the ABS, thereby eliminating the need for a separate crown adjust operation and to reduce costs, as well as allowing the selection of new slider materials which previously have been unable to used with heretofore known crown adjust processes.